[nakkaya]

Author here. I am actually curious about this myself. I originally released it under GPL but then on another HN thread someone said anything compiled with it also ends up being GPL, so I switched to BSD 2 Clause. I have not copy pasted code from Clojure compiler BUT in order to keep the Ferret semantics the same as Clojure semantics algorithms are identical. [1] shows + function in Ferret and Clojure. As for data structures situation is similar, same semantics implemented in C++ instead of Java with some differences/tweaks geared towards embedded systems.

[1] https://gist.github.com/nakkaya/7050d5daf2c7034a25bb079658d8...

[e12e]

Nothing wrong with BSD - but as for a GPL compiler with a run-time, you could also look at the GCC/GNU libc licensing (GPL/LGPG). I do think it's important people are aware that GPL on things with a run-time should probably have an exception/use something like the LGPL - as you generally don't want "documents"/artifacts produced with a tool, to forcefully inherit the license of the tool used for creating them (eg: You don't want the word processor to force a license on documents produced, or the drawing application apply license to images - and the same goes for programming languages, IMNHO).

On another note, I'm not sure it would be quite possible to stretch "copyleft" that far legally anyway - but that's another discussion - and at ending up with an invalid license isn't really any good either, as that would leave you with just copyright and no license grant - making the tool illegal to copy/distribute...

[dkersten]

LGPL isn't enough for a runtime unless your entire runtime is dynamically linked. Either GPL or LGPL with runtime exception works fine though (that's what libc and others have, I believe).

That is, they added an exception saying that if you use it in a certain way (unmodified, runtime for compiled code), then it's exempt from many of the GPL's clauses. Used in any other way, however, and you must comply with the (L)GPL

[rrix2]

I'm not a lawyer but my understanding is that copying semantics could still be argued as creating a derivative work. This is what e.g. Whisper Systems claimed before publishing an axolotl spec, that anyone implementing the spec was doing so by deducing the semantic meaning of a copyleft piece of software and thus was a derivative work of said copyleft piece of software. This meant that the resulting binary was covered under the copyleft license (GPLv3 in that case, but my understanding of EPL is similar) https://medium.com/@wireapp/axolotl-and-proteus-788519b186a7

I don't know if Rich or the other Clojure copyright holders care enough to ever make trouble, but I'm pretty sure most companies with a decent legal team would think thrice before offering a piece of code built using Ferret

GCC has already solved the problem the other commenter you mention brings up with the runtime library exception https://www.gnu.org/licenses/gcc-exception-faq.html but I don't know if you can tack this on to the clojure-derived parts of ferret. I sure wish SFLC or someone was able to do legal counselling for new/small projects like this, I feel like a big reason people shy away from copyleft isn't the hippie dippie bullshit but because these interactions are impossible to reason about by laypersons